Antibodies play a central role in molecular biology, clinical diagnostic research and therapeutic medicine. As a result, demand for innovative methods for producing highly specific and higher affinity antibodies, at lower cost, has increased, and is particularly critical nowadays because of the need to protect public health from harmful agents which may be used in a bio-terrorist attack. Over the last ten years, the Co-principal investigator has studied the structure-function relationships in antibodies, describing a correlation between the antigen-binding site topography and the kind of antigen the antibody interacts with. The goal of this research is to explore whether this correlation can be used to create antigen-binding site repertoires optimally suited for recognition of peptides and proteins. Such repertoires should increase the frequency of obtaining highly specific antibodies, and most likely, higher affinity antibodies, as suggested by the preliminary results reported in this application. To implement this novel approach, two topography-biased repertoires have been designed: one of flattened antigen-binding sites and the other of grooved ones. These repertoires will be constructed as scFvs (single chain variable fragment)-plll proteins to be displayed on filamentous phage. The resultant libraries will be screened against a panel of diverse antigens, representing peptides, small proteins and proteins. The expectation is that peptides, and probably small proteins, select higher affinity scFv at a higher frequency from the grooved antigen-binding site library. Typical proteins should do so from the flat library. Most of the molecules included in the panel of antigen models have been well characterized in terms of their three-dimensional structure and antigenic surface, and are also of biomedical interest. For instance, the libraries will be screened with the allergen for latex (Hevea brasilian), the toxin of one of the most lethal scorpions known (Centruroides noxius) and the biological active compound of the black widow spider (Latrodectus tridecimguttatus) venom. As these antigens are structurally well-characterized, the analysis and interpretation of the results will be facilitated. The biomedical relevance of these antigens will make the scFv obtained potentially useful in the protection of public health. Furthermore, this study will lay the foundation for further development of highly specific and high affinity antibodies to a diverse array of toxins.